He was named ambassador to Mexico when Ronald Reagan, a like-minded conservative Republican who had also been president of the actors guild, entered the White House in 1981. Mr. Gavin had been active in Reagan’s 1980 presidential campaign.

Amid complaints from veteran diplomats that American embassies were still being turned over to financial backers and unqualified amateurs, the selection of an actor and friend of the president for one of the nation’s most sensitive diplomatic posts was met with dismay in Mexico. Officials there sardonically jested about sending the comedian Cantinflas to Washington in retaliation.